<title>集合的前N个元素</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cm">/*</span>
<span class="pl-cm">225</span>
<span class="pl-cm">*/</span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;cstdio&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;queue&gt;</span><span class="pl-cp"></span>
<span class="pl-k">using</span> <span class="pl-k">namespace</span> <span class="pl-n">std</span><span class="pl-p">;</span>
<span class="pl-kr">inline</span> <span class="pl-kt">void</span> <span class="pl-nf">print</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">n</span><span class="pl-p">){</span><span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d &quot;</span><span class="pl-p">,</span><span class="pl-n">n</span><span class="pl-p">);}</span>
<span class="pl-kr">inline</span> <span class="pl-kt">void</span> <span class="pl-nf">print</span><span class="pl-p">(</span><span class="pl-kt">char</span> <span class="pl-n">n</span><span class="pl-p">){</span><span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%c&quot;</span><span class="pl-p">,</span><span class="pl-n">n</span><span class="pl-p">);}</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">(){</span>
        <span class="pl-n">freopen</span><span class="pl-p">(</span><span class="pl-s">&quot;element.in&quot;</span><span class="pl-p">,</span><span class="pl-s">&quot;r&quot;</span><span class="pl-p">,</span><span class="pl-n">stdin</span><span class="pl-p">);</span>
        <span class="pl-n">freopen</span><span class="pl-p">(</span><span class="pl-s">&quot;element.out&quot;</span><span class="pl-p">,</span><span class="pl-s">&quot;w&quot;</span><span class="pl-p">,</span><span class="pl-n">stdout</span><span class="pl-p">);</span>
        <span class="pl-kt">int</span> <span class="pl-n">n</span><span class="pl-p">,</span><span class="pl-n">c</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span>
	<span class="pl-n">queue</span><span class="pl-o">&lt;</span><span class="pl-kt">int</span><span class="pl-o">&gt;</span> <span class="pl-n">x</span><span class="pl-p">,</span><span class="pl-n">y</span><span class="pl-p">;</span>
	<span class="pl-n">x</span><span class="pl-p">.</span><span class="pl-n">push</span><span class="pl-p">(</span><span class="pl-mi">1</span><span class="pl-p">);</span>
	<span class="pl-n">y</span><span class="pl-p">.</span><span class="pl-n">push</span><span class="pl-p">(</span><span class="pl-mi">1</span><span class="pl-p">);</span>
        <span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d&quot;</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">n</span><span class="pl-p">);</span>
	<span class="pl-k">while</span><span class="pl-p">(</span><span class="pl-n">c</span><span class="pl-o">++&lt;=</span><span class="pl-n">n</span><span class="pl-p">){</span>
	        <span class="pl-kt">int</span> <span class="pl-n">a</span><span class="pl-o">=</span><span class="pl-n">x</span><span class="pl-p">.</span><span class="pl-n">front</span><span class="pl-p">(),</span><span class="pl-n">b</span><span class="pl-o">=</span><span class="pl-n">y</span><span class="pl-p">.</span><span class="pl-n">front</span><span class="pl-p">(),</span><span class="pl-n">next</span><span class="pl-p">;</span>
                <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">a</span><span class="pl-o">&lt;</span><span class="pl-n">b</span><span class="pl-p">){</span>
                        <span class="pl-n">print</span><span class="pl-p">(</span><span class="pl-n">a</span><span class="pl-p">);</span>
                        <span class="pl-n">x</span><span class="pl-p">.</span><span class="pl-n">pop</span><span class="pl-p">();</span>
                        <span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-n">a</span><span class="pl-p">;</span>
                <span class="pl-p">}</span> 
                <span class="pl-k">else</span> <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">a</span><span class="pl-o">&gt;</span><span class="pl-n">b</span><span class="pl-p">){</span>
                        <span class="pl-n">print</span><span class="pl-p">(</span><span class="pl-n">b</span><span class="pl-p">);</span>
                        <span class="pl-n">y</span><span class="pl-p">.</span><span class="pl-n">pop</span><span class="pl-p">();</span>
                        <span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-n">b</span><span class="pl-p">;</span>
                <span class="pl-p">}</span>
                <span class="pl-k">else</span><span class="pl-p">{</span>
                        <span class="pl-n">print</span><span class="pl-p">(</span><span class="pl-n">a</span><span class="pl-p">);</span>
                        <span class="pl-n">x</span><span class="pl-p">.</span><span class="pl-n">pop</span><span class="pl-p">();</span><span class="pl-n">y</span><span class="pl-p">.</span><span class="pl-n">pop</span><span class="pl-p">();</span>
                        <span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-n">a</span><span class="pl-p">;</span>
                <span class="pl-p">}</span>
                <span class="pl-n">x</span><span class="pl-p">.</span><span class="pl-n">push</span><span class="pl-p">(</span><span class="pl-mi">2</span><span class="pl-o">*</span><span class="pl-n">next</span><span class="pl-o">+</span><span class="pl-mi">1</span><span class="pl-p">);</span>
                <span class="pl-n">y</span><span class="pl-p">.</span><span class="pl-n">push</span><span class="pl-p">(</span><span class="pl-mi">3</span><span class="pl-o">*</span><span class="pl-n">next</span><span class="pl-o">+</span><span class="pl-mi">1</span><span class="pl-p">);</span>
	<span class="pl-p">}</span>
	<span class="pl-k">return</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
</cpde></pre></div>